Using Piezoelectric Technology to Reduce our Carbon Footprint

Climate change is a major problem facing our society and it is our responsibility to fix it. In 2006, the greenhouse gas emissions of the District of Columbia totaled about 10.5 million metric tonnes. Over the past several years, the city has done much to lower their carbon footprint, but more action can be taken to try to reduce our effect on climate change. The piezoelectric effect is the ability of certain materials to generate an electric charge in response to applied stress or pressure, which can be produced by foot steps. The energy can be accumulated in certain solid materials, such as crystals and ceramics. The transducers would be placed under tiles and walkway coverings where energy can be transferred to an external battery. In DC, hundreds of thousands of employees and tourists walk through the city every day. Using piezoelectric transducers, placed in commonly visited locations in DC, we can use daily foot traffic and convert the stresses into useful energy. To decrease electrical energy consumption in the area, we can implement piezoelectric generators in commonly visited locations in DC, such as the metro station and near popular tourist attractions, collecting as much energy as possible. Our ultimate goal is implement the transducers in DC, but we will start small in the hallways of our high school. The product can be mass produced cost efficiently and harvest enough energy to support DC and other local areas, using otherwise inconsequential foot steps to lower our overall carbon footprint.

Using Piezoelectric Technology to Reduce our Carbon Footprint

Climate change is a major problem facing our society and it is our responsibility to fix it. In 2006, the greenhouse gas emissions of the District of Columbia totaled about 10.5 million metric tonnes. Over the past several years, the city has done much to lower their carbon footprint, but more action can be taken to try to reduce our effect on climate change. The piezoelectric effect is the ability of certain materials to generate an electric charge in response to applied stress or pressure, which can be produced by foot steps. The energy can be accumulated in certain solid materials, such as crystals and ceramics. The transducers would be placed under tiles and walkway coverings where energy can be transferred to an external battery. In DC, hundreds of thousands of employees and tourists walk through the city every day. Using piezoelectric transducers, placed in commonly visited locations in DC, we can use daily foot traffic and convert the stresses into useful energy. To decrease electrical energy consumption in the area, we can implement piezoelectric generators in commonly visited locations in DC, such as the metro station and near popular tourist attractions, collecting as much energy as possible. Our ultimate goal is implement the transducers in DC, but we will start small in the hallways of our high school. The product can be mass produced cost efficiently and harvest enough energy to support DC and other local areas, using otherwise inconsequential foot steps to lower our overall carbon footprint.

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Judges’ Queries and Presenter’s Replies

Arturo Gutierrez

Judge

June 8, 2015 | 12:38 p.m.

Great concept! I have a couple of questions about piezoelectrics.

1. Do you know the reason(s) that piezoelectric technology is not more widely used for this application? In other words, what are some of the challenges in implementing this technology for this application?

2. How did you arrive at the value of the average student body generating 36 kW-hr per day?

Karl Zhao

Co-Presenter

June 8, 2015 | 10:47 p.m.

Both excellent questions.
1. We suspect the main reason piezoelectric technology is not yet widely used is because the technology is comparatively much more obscure than traditional power generation techniques. As such, not many have attempted to implement this technology in a form practical for this application. However, there have in fact been schools and other facilities that have already started using this technology to aid in power generation, such as the Simon Langton Grammar School in Cantebury, England. (http://news.nationalgeographic.com/news/energy/...)
The main challenge to implementing this technology on a larger scale is the cost. Our concept utilizes two sheets of copper, one sheet of glass, and one layer of a chemical called barium titanate. Glass is costly to produce in large sheets, and barium titanate is costly to purchase in large quantities. Because of that, the cost of covering an entire facility in these transducers would likely be an impractical cost for some.
However, many different variations of the piezoelectric transducer exist, some with lower costs than others. We’re sure if an effort is made, an alternative design utilizing the same principle that is more cost efficient and could be mass produced more easily would be found.
2. We found through various sources that using our form of the technology, a 60KG person, assuming every footstep could be captured, could generate 9 W on transducers consistently. We assumed a student would walk around and move on the floor of their school for approximately 2 hours per day (as time spent sitting in a seat cannot be used to generate energy), so a student would generate 9 W-hr per hour for 2 hours per day, or 18 W-hr per day total. Assuming an average school body of 2000 students, the total generated by a student body over a single day would be 36 kW-hr per day.
The main issue with this calculation is that it assumes every single footstep by every student will be captured, including the ones taken outside of the school building. A more realistic number would be lower, though we expect not by much.

I think your idea of harvesting energy from the footsteps of pedestrians could be an important aid in changing how our electricity is generated. I have two questions about why you chose to implement your idea this way:

1) Given the price of piezoelectric materials did you consider embedding the power generation in people’s shoes rather than the flooring tiles? This could possibly be less expensive and then you would also never miss a step when the passengers walked somewhere your tiles weren’t placed.

2) Did you consider alternate methods besides piezoelectrics for harvesting energy using flooring tiles? Would a magnetic induction generator (like those used in windmills) be comparable in price or efficiency?

Karl Zhao

Co-Presenter

June 8, 2015 | 10:50 p.m.

Both are very plausible ideas.
1. We in fact did do research on this possibility. However, for us, it became an issue of how useful it was rather than how much money it could save. Embedding piezoelectric transducers into shoes would also require a battery placed inside the shoe itself, and a standard nickle or lithium battery that size would not be able to store much power. Beyond a certain point, all power generated through the footsteps would be wasted. In addition, it’s likely that power generated from piezoelectric sensors in shoes would only power phones, tablets, and other small mobile devices, which draw a minimal amount of electricity in the first place. By placing transducers into floor tiles instead, despite the higher initial cost, more energy could be generated and overall the positive impact on the environment could be greater.

2. A standard induction generator requires rotational motion of a rotor, which we do not know how we would implement. In addition, the parts required would likely add up to a larger cost than the parts of a standard piezoelectric transducer. Because of this, we believe that even though power generation through electromagnetic induction may result in more power, ultimately, utilizing the piezoelectric effect is a much more practical and cost efficient method.

Of course, such an approach could be very possible, given the right circumstances. We aren’t disregarding the idea entirely.

Daniel Jones

Judge

June 9, 2015 | 09:42 p.m.

Would a stairway be a good place to try and demonstrate the efficacy of your approach? I can think of one long, steep subway staircase in Cambridge, MA that requires a lot of work to stomp your way to the top. If there was a visual to show the electric energy produced it might challenge people to climb as opposed to riding the escalator. Any thoughts on this as a demo? At a minimum you could keep a defibrillator charged up.

Rachel Qian

Co-Presenter

June 9, 2015 | 10:20 p.m.

Implementing piezoelectric transducers into stairways is definitely a good way to demonstrate our approach to creating energy. We aim to place the transducers in areas of high foot traffic and busy subway stations are an example. As we further develop the idea, we can create empowering visuals and service announcements that encourage the audience to take part in reducing carbon emissions. Our idea solely depends on the participation of the people, so it is important that they understand the impact that could result from their simple actions.

This is a very interesting concept. I have a couple questions for the team:
1. What benefit does installing these transducers in D.C. have over installing them in other large cities, for example New York City?
2. Have you taken into consideration the amount of conventional fossil fuels that will be burnt to build and install the transducers? How long would it take for the tiles to generate more energy than it required to make and install them?

Amelia Cherian

Lead Presenter

June 11, 2015 | 11:30 p.m.

Ms. Luff, thanks for your comment! We agree, installing the transducers in any major city would definitely be a great idea. There is so much energy we could gather with the great deal of foot traffic that cities experience. We wanted to begin closer to home, which is why we suggested implementing the transducers in D.C. first, but this idea could certainly be applied in any other city. Though there will inevitably be an initial cost and energy needed to install the transducers, the energy we could generate with the many footsteps taken in the cities would vastly reduce the amount of fossil fuels we need to use in the future. Within a short amount of time, that energy would make up for the fossil fuels we used to execute this and after that point, this would be a source of clean energy. And in the long-run, this could be used to counteract our effect on climate change.

Further posting is closed as the competition has ended.

Presentation Discussion

Callie Cook

This idea is very interesting however it seems as though it would take a lot of money and time to install. If a school were to install this how exactly would they? Would they have to rip out all of the existing tile/carpet floors, put down your product, then re-tile/carpet? Many public school systems don’t have enough money as it is to keep there doors open let alone update their floors. How much would it cost a school to install this product? How many schools do you predict are able and willing to install this product?

Karl Zhao

Co-Presenter

June 9, 2015 | 10:27 p.m.

Excellent question. The cost is in fact prohibitive for a large amount of schools. Indeed, if implemented properly, the school would need to have its existing tile and carpet removed before the transducers could be placed. However, the ultimate goal of this idea is to utilize them in much more heavily traversed areas such as crowded city subway stations or possibly even roads or highways. Installing them in schools would help, but would mainly show the potential for much greater impact once installed in the other areas mentioned. Because of that, we don’t see it as critical that every school has these installed; even if just a few relatively well funded schools have these installed, if it’s demonstrated to be effective, we’d consider it a success.

Callie Cook

If a few schools implemented this technology it has the potential to create a ripple effect throughout schools across the country. I could really see this design being recognized by influential critics to increase its popularity.
This would work well in crowded areas indeed. However it may be tricky to shut down busy areas to install this. How long does it take to install?

Peggy Owens

Guest

June 9, 2015 | 03:22 p.m.

This is a great idea. Even if it isn’t feasible to add it to exiting schools, it would be great to have it installed in new schools when they are built! I LOVE that our youth are thinking about this and coming up with solutions to problems my generation helped cause. You go PHS students!!!

Brian Drayton

Co-Director

June 10, 2015 | 08:12 a.m.

I enjoyed this paper & presentation. Seems like piezo-electricity is a popular idea in this competition! Have you checked out the poster on “harvesting energy from subways” (by Anusha Dixit)? You all might have an interesting conversation.

Callie Cook

You are right that piezo-electricity is very popular in this competition. I knew almost nothing about piezo-electricity before. It was interesting to learn about it and see all the ways it could potentially be used!

Caroline Leng

Looking at your video and paper, I don’t see any mention of transducer size. Have you researched into that, and if so, how many piezoelectric transducers would you expect to be installed per square meter? Furthering this, what would the price be for installation per square meter? How many watts could be generated per square meter at peak hours?

Joseph Thomas

Guest

June 11, 2015 | 05:41 p.m.

The technology sounds very promising for a world that is so much in need of clean energy.

Joshua Mathews

Guest

June 11, 2015 | 05:42 p.m.

I have a difficulty in opening the video. Nevertheless, what would be the estimated reduction carbon emission by piezo -electricity as compared to electricity derived from fossil fuel.